This material is called Ethylene-vinyl acetate (EVA), it is similar to a thermoplastic and it is very soft and flexible. Ideal to make light armor. You can find it in different thicknesses and shapes. You can usually buy 3mm foam, called craft foam, in paper shops or art shops very cheap (1€ or less for a very big sheet). Thicker foam can be found on the mats you use for camping (4 - 5 € a mat) and even thicker and harder mats for kids use this material (10 - 12 € for 6 puzzle mats). The best characteristic of this material is that it can be molded with heat and it keeps the shape! (it has its limitations tho) the bad news is that any marks and indents will probably stay there if you are not carefull while you wear it.

Another trick, sometimes you need several layers of foam to get a 3D effect, if that is so cut one piece and use that piece as a pattern you will minimize any possible slip of your scissors when you cut the first one (you can also cut both at the same time)Otro truco, a veces se necesitan diferentes capas de foam para dar un efecto 3D, si es así cortad la primera pieza y usadla de patrón para la siguiente, de esa manera minimizaréis cualquier posible fallo que hayáis tenido con las tijeras cuando cortasteis la primera (también podéis cortar las dos piezas a la vez)

Shaping

Forma

As I said before you can shape foam with heat, for small pieces an iron works great but do be careful as the corners will roll up too much if you overdo it, for black widow I used this technique to give the belt a convexe form, works great for corners you want to make smooother. You can't use the iron directly over the foam or it will really melt, put a paper or a piece of fabric between them. My black cat mask and the knee pads of my vampire are also shaped like that

I don't have a heat gun, but my heater works as well, even a hair dryer could work for this but it would be a bit less comfy to use. Basically for this kind of sharp detail you just need to heat your foam and fold it, try to pinch it but be careful with the nails. Don't worry about going hard on it as it opens again if you don't glue it

If your piece is really big you may consider putting wires inside appart from the heat in order to keep the shape. Here I glued a wire to the inside (bottom) and covered it with a ribbon to secure it (sorry no good pics, the ribbon is under)

Obviously you can use a base and mold your foam over it, this works best with round parts and polystyrene balls for example, with my black cat mask I used my own face as base, the material gets cold quickly so you should be fine if you are careful and wait a couple of seconds after applying the heat. Little pieces under the foam will shape it.

If your shape is extreme you may need to make several cuts to get the proper shape, if you have further details on top these cuts won't be noticeable (same as if you are very careful and clean when you glue it) Remember that small pieces are always easier to mold.

GlueingPegadoThe best glue you can use for foam silicon, you have cold silicon, which works great with foam but it needs time to dry. The other good option is hot glue, it dries very quickly but it has a problem, as it uses heat you need to be careful when you apply it as you can slightly bend the material or get uneven shapes if the glue dries too quickly. E6000 is always a good solution as it is very very strong and flexible but again dries slowly. Superglue is about the worst option, it isn't elastic and it will probably crack, specially in edges, also, if you don't get it right first time it creates a layer of glue that will be very difficult to reglue.El mejor pegamento que podéis usar es la silicona líquida, funciona genial con el foam pero necesita tiempo para secar. La otra buena opción es la silicona caliente, se seca muy rápido pero tiene un problema, como usa calor podríais deformar la goma EVA si no tenéis cuidado o incluso se puede quedar una forma rara si se enfría muy rápido. El superglue es quizá la peor opción, no es elástico y probablemente se romperá, especialmente en las esquinas. Si no se pega la pieza bien a la primera os será casi imposible volver a pegarla porque crea una película de pegamento por encima del material que no se adhiere a nada más.

DetailingDetallesWhen you make armour you may need to do an edge to the foam, this can be done with 3D glue or fabric paint or also with hot glue. Obviously you can do drawings as well.Cuando hacéis armaduras es posible que necesiteis hacerles un filo, esto se puede hacer con pintura o pegamento 3D o también con silicona caliente. Obviamente también podéis hacer dibujitos

An advantage of the foam is that you can sew it perfectly well, some rough details can be done like that, or you can also glue cord to it